E-ink display devices can display image by controlling an electric filed to change a distribution of charged particles so as to change reflectivity of the ambient light. Base on the above display principle, the E-ink display devices have bistability and do not need the additional light source. Therefore, the E-ink display devices have a high power-saving feature, so the E-ink display devices can meet the need of modern technology on the display devices.
FIG. 1 is a schematic cross-sectional view of a conventional E-ink display device. Referring to FIG. 1, the E-ink display device 100 includes an active element array substrate 110, an E-ink layer 120, a waterproof film 130 and a sealant 140. The E-ink layer 120 is disposed on the active element array substrate 110. The waterproof film 130 is disposed on the E-ink layer 120, so that the waterproof film 130 can cooperate with the sealant 140 that surrounds the E-ink layer 120 to prevent outside moisture from entering the E-ink layer 120. However, a waterproof performance of the sealant 140 is worse than that of the waterproof film 130, and the outside moisture tends to penetrate into the E-ink layer 120 through the sealant 140.
To improve the waterproof performance of the E-ink display device, a conventional approach is that the sealant 140 is extended to a top of the waterproof film 130 from a periphery of the E-ink layer 120, as shown in FIG. 2A. As such, a path from which the outside moisture may penetrate into the E-ink layer 120 through the sealant 140 can be prolonged. Another conventional approach is that the waterproof film 130 with a relatively larger size is disposed on the E-ink layer 120, as shown in FIG. 2B. As such, a path from which the outside moisture may penetrate into the E-ink layer 120 through sealant 140 can be prolonged.
However, in the above two approaches, air bubbles 150 may be generated easily between the E-ink layer 120 and the sealant 140 in a process of forming the sealant 140. The air bubbles 150 would degrade the waterproof performance of the E-ink display device 200. Furthermore, in the subsequently process of heating to cure the sealant 140, thermal expansion of the air bubbles 150 may make the sealant 140 break, and that would decrease process yield of the E-ink display device 200. To avoid generating the air bubbles 150, coating speed for forming the sealant 140 needs to be reduced so as to prolong exhaust time in the process of forming the sealant 140. However, if the exhaust time is prolonged, the production rate of the E-ink display device 200 would be decreased, and thus the production cost of the E-ink display device 200 would be increased.